共查询到20条相似文献，搜索用时 62 毫秒
1.
| 1. |
The prefabricated cutoff wall as one of the economically justified designs can be regarded as the main watertight element of an earth dam.
| | 2. |
The cutoff wall can be made from precast asphaltic concrete and concrete blocks and combined — from both joined together on asphalt mastic. An analysis of the stress-strain state showed that each of these walls has a sufficient margin of deformability.
| | 3. |
The cutoff wall of precast concrete blocks, eliminating the use of asphalt for its construction and having a practically unlimited margin of deformability, can be of interest to designers and builders.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 11–14, November, 1993. 相似文献
2.
Conclusions
| 1. |
Destruction of the concrete of the dam in the transition section between the spillway face and stilling basin occurred because
of changes in the technology of carrying out the concreting operations.
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| 2. |
The crack in the dividing pier of the overflow dam occurred because of the wrongly selected profile of the foundation and
substantial change in its stress state force and after construction.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 32–33, March, 1999. 相似文献
3.
| 1. |
The construction ana operation of the upstream wing wall of the Tashkumyr hydroelectric station confirmed the possibility and expediency of using lean rollcrete and simple designs for dams. After 3 years' operation the wall is in a completely satisfactory state.
| | 2. |
The use of rollcrete with a cement content of 80–120 kg/m3 during concreting by the technology proposed and perfected during construction of the wall provided the obtainment of concrete grades M100180–M200180 (classes V7.5–V15). When designing rollcrete it is necessary to take into account its increased nonuniformity — the coefficient of variation of the strength values of the concrete of the wall was 0.20–0.25.
| | 3. |
A uniform temperature regime with low values of the maximum temperatures is characteristic for rollcrete masonry. The measured temperature of the wall masonry corresponded to those calculated. The possibility of predicting the temperature regime of the rollcrete mass during its construction is thereby confirmed.
| | 4. |
When designing hydraulic structures it is necessary to take into account the anisotropy of the density of rollcrete masonry. Horizontal joints have a high permeability, which requires either a special technology of forming them or structural protection of such masonry with the outer zones made of vibrated concrete.
It is expedient to protect the rollcrete masonry with a gunite layer mainly for temporary dams. 相似文献
4.
| 1. |
Processes of variation of the dam-foundation-abutments system are not fading away, the operating regime of the structure has not stabilized.
| | 2. |
The unsteady and inelastic work of the bank abutments, evidently, is one of the causes of irreversible radial movements and development of fracturing in the first column of the dam.
| | 3. |
Cracking on the upstream face and progressive seepage through the concrete of the first column worsen the state of the concrete and the cracks are subject to healing by polymer materials. Polymer injections do not improve the work of the structure, but if the cracks are not healed promptly the volume of necessary repair works will increase with the course of time.
| | 4. |
To evaluate the stress state of the dam it is necessary to make calculations with consideration of the large stress raisers: water intakes, gate grooves, etc.
| | 5. |
It is required to evaluate the fact of the excess by a factor of 2–3 of the increments of the maximum arch stress over the design values in various load ranges.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 4, pp. 21–25, April, 1994. 相似文献
5.
| 1. |
The reinforced-concrete panels of the new design covering the entire plane of the section joint with the grouting fittings and groutstops built into them were one of the main elements of the new tierwise technology of concreting, which made possible the use of this technology when constructing the arch dam, shortening of the cycle of operations on each block and tier of the dam, and achievement of a record rate of growth of the dam.
| | 2. |
The combined solution of design and technological problems on the basis of a thorough study of available experience made it possible to create a design of panels technologically easy to manufacture and install, which provided the high quality of the work on constructing and sealing the dam.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 17–19, March, 1989. 相似文献
6.
| 1. |
The most substantial and sharp changes in the state of the rock-concrete contact appeared beginning in 1985 after reaching 76% of the design hydrostatic load.
| | 2. |
Opening of the rock-concrete contact is distinguished by a nonuniform rate of change with time and nonuniform distribution of the amplitude of opening along the front of the dam, which reflects the complex interaction the dam with the foundation and effect of inhomogeneity of the foundation and different technological conditions of placing the contact concrete.
| | 3. |
Opening of the rock-concrete contact is accompanied by substantial changes in stresses and strains in the rock and concrete of the contact zone and in the piezometric heads in the foundation, reflecting structural changes in it during interaction of the dam with the foundation.
| | 4. |
In addition to the effect, which occurs for all types of concrete dams on a rock foundation, of technological factors and design differences of individual parts of the dam on the behavior of the contact zone of the foundation and concrete of the Sayano-Shushenskoe dam, also noted are such features as active opening of the rock-concrete contact over the entire length of the channel part of the foundation, presence of signs of hanging of the arch on the first columns on the banks, and a special stress state of the concrete in the lower part of the upstream face, which can be a reflection of the design features of the gravity-arch dam.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 44–49, October, 1991. 相似文献
7.
| 1. |
Absorbing formwork has a substantial effect on concrete quality for concretes with W/C0.365.
| | 2. |
The concrete surface quality depends on the quality of the absorbing formwork materials used.
| | 3. |
The possible amount of water removed from the concrete by means of the absorbing (vacuum) formwork was 2.4–3.57 kg/m2.
| | 4. |
Before the start of hardening of the concrete, its water content decreases by 20–30% at a depth to 15 cm from the absorbing formwork. During hardening of concrete, its water content equalizes over the entire length of the specimen (thickness of the block), and under these conditions the W/C ratio of the concrete near the formwork is not more than 1% below the initial.
| | 5. |
According to the results of testing the concrete for cavitation resistance, the best indices were noted for formwork containing ensonite. In this case, the cavitation resistance of the concrete was increased up to 1.4 times. The latter circumstance permits recommending for use as formwork absorbing material fine-porous paperboard of the ensonite type (with pore sizes 20–100 Å), which freely passes water molecules but retains cement particles.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 39–41, November, 1989. 相似文献
8.
| 1. |
Geodynamic movements of surrounding rock masses can affect the behavior of arch dams. Creep movements of slopes can cause a change in the former scheme of static behavior of a dam, being expressed in a different reaction to the previous combination of acting loads.
| | 2. |
The effect of seismotectonic activity during the earthquake precursory period is manifested in the form of fluctuations of the on-site data: strain-gauge, geodetic, and piezometric. The location of the detector that recorded fluctuations and values of these fluctuations characterize the temporal change in the scheme of static behavior of the dam reacting to deformation of the blocks and slabs of the surrounding masses.
| | 3. |
For concrete dams constructed in narrow mountain canyons, it is necessary to conduct on-site observations according to a special program compiled on the basis of an analysis of the state of the dam in the first years of operation to detect geodynamic and seismotectonic activity. These observations should be informative for: Determination of the effect of the surrounding rock masses on the state of the dam; study of the role of technogenic factors in natural processes; selection of earthquake precursors; determination of the seismic stability of the dam.
| | 4. |
On all dams constructed in mountain canyons it is necessary to make a retrospective analysis of the on-site data to determine the interrelations in the reservoir-dam-surrounding rock mass system.
| | 5. |
The data of on-site observations of the responses of a dam to geodynamic and seismotectonic processes can be used by basic science for gaining knowledge about the earth's crust.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 20–23, July, 1993. 相似文献
9.
The concrete dam and rock foundation of the Zeya hydroelectric station after operating for 6 years, during which the reservoir was filled to the NPL and in some years somewhat exceeded it, is in a satisfactory state. | 2. |
The behavior of the dam under the effect of the operating loads and climatic factors correspond to the design assumptions.
| | 3. |
The indices of the state of the Zeya buttress dam give grounds to state that dams of the given type are prospective for use under conditions of a harsh climate.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 9–13, May, 1993. 相似文献
10.
| 1. |
An analysis of the data of on-site observations in 1990–1993 showed that after a fourfold rise of the water level in the reservoir of the Sayano-Shushenskoe dam, a tendency toward stabilization of most monitored parameters characterizing the static behavior of the structure was noted.
| | 2. |
The increase of the irreversible component of radial displacements, tilts, and stresses in concrete slowed. The opening at the rock-concrete contact during seasonal rises of the upper pool level is gradually stabilizing, and the depth of opening (from the upstream face) is not increasing. Although the seepage discharges through the foundation during the last four years increased, the rate of increase decreased by the end of the indicated period.
| | 3. |
An increase of drainage discharges and a change in the piezometric heads (sometime anomalous) with the same upper pool levels indicate continuing changes in the stress state in the dam foundation, which is causing the formation of cracks in the rock mass.
| | 4. |
The magnitude and character of the change in stresses in the arch abutments and strains in the rock mass of the bank abutments indicate that the actual yielding of the banks was greater than was assumed in the design.
| | 5. |
Opening of horizontal joints and cracks on the upstream face within the 50-m zone from the contact during seasonal rises of the UPL to the NPL is continuing. Here a tendency toward penetration of the opening into the depths of the concrete mass is observed. The character of variation of the cantilever stresses at the upstream face in recent years indicates opening of horizontal joints and cracks at elevations higher than 50 m from the base of the structure.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 42–45, October, 1994. 相似文献
11.
| 1. |
Conversion of the gravity dam from traditional to reduced shapes can be effected with a more complete utilization of the compressive
strength of the concrete and by permitting cracks to open in its upstream face.
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| 2. |
The following structural measures should be taken to guarantee the stability and strength of the type of dam proposed: a)
the installation of a lining along the upstream face and a system of drains developed behind it; b) carrying the grout curtain
upstream and joining it with the dam.
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| 3. |
The set of computations performed and the model studies conducted confirmed the strength and stability of the dam design that
we developed.
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| 4. |
The proposed design makes it possible to reduce the volume of concrete and the cost.
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相似文献
12.
| 1. |
Grout curtains are a structural element of the underground contour of dams with a limited service life. A gradual decrease of the modulus of deformation of the foundation and deterioration of its other characteristics occur as a result of leaching of the cement.
| | 2. |
Estimation of the life of grout curtains and determination of the overhaul period should be carried out differentially on the basis of particular values of the rate of the leaching process. For example, the average rate of removal of calcium oxide from the grout curtain in the foundation of one section of the Sayan-Shushenskoie dam is 7.5 and of the Zeya dam, 9.4 mg/sec.
| | 3. |
It is necessary to broaden the study of the behavior of grout curtains at operating concrete dams to establish performance criteria at various stages of life of the structure.
| | 4. |
The volume of grouting works on a grout curtain should be assigned on the basis of the required life of grout curtains, assuming that the life is proportional to the square of their thickness.
| | 5. |
When designing the underground contour of dams, the parameters of the drainage system should be assigned with consideration of the destruction of the grout curtains occurring and prevention of overloading of the drainage systems. At the dam designing stage it is necessary to provide the possibility of conducting effective restoration of the serviceability of grout curtains.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 21–24, July, 1992. 相似文献
13.
| 1. |
To reduce the cost and construction time of hydro developments, it is necessary to introduce more widely continuous concreting technologies. Concreting of heavily reinforced and thin-walled structures and members is most effectively done with cast concrete mixes by means of modern concrete pumps.
| | 2. |
As a result of experimental investigations of pipeline delivery of mixes by BN-80-20 concrete pumps, the values of the specific resistances during pumping of various compositions of the mixes and the local resistances of quick-disconnecting pipe connections were determined; recommendations were developed for calculating the distance of pipeline transport of the mixes by the concrete pumps; the values of Kf, the volume filling of the transport cylinders of the concrete pump with the plasticized concrete mix, and Kd, the inertial component of the pressure during displacement of the mix, were refined.
| | 3. |
The two-year experience of using the means (conveyors, concrete pumps) of craneless technology of placing concrete for construction of the powerhouse of the Shul'binsk hydro development showed that even with the high price and underutilization of the potential possibilities of the equipment and mechanisms, a considerable savings was obtained due to shortening of the construction time and start-up of the first unit of the hydrostation ahead of schedule.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 38–43, October, 1990. 相似文献
14.
| 1. |
The adopted scheme for discharge of the construction flows through the Hoabinh hydraulic development site has proved to be reliable, and it can be recommended for construction of hydraulic projects under conditions with seasonally repeated rain floods and a clearly defined and stable low-water period.
| | 2. |
The combined scheme for discharge of the flows through the diversion tunnels and canal made it possible to carry out the work in the diversion canal zone for construction of the dam fills, grouting of the dam base, and other work, with subsequent discharge of the rainy season flood through the diversion canal at increased levels.
| | 3. |
Construction of the temporary concrete spillway at the end of the canal in the zone in which the downstream wedge of the dam ends made it possible to discharge the 1986 floods with a peak flow of 14,500 m3/sec and with a specific discharge of 180 m2/sec (the maximum over the construction period) without damage to the dam fills, since the scouring velocity was developed beyond the downstream structure limits. The constructional solution for discharge of the river flows through the partially constructed rock-earth dam can be recommended for use in the hydraulic engineering practice.
| | 4. |
Use, in the construction flow discharge scheme, of the deep sluices of the spillway head structures, located approximately in the central part of the dam height, can be recommended as a permanent or temporary solution for similar cases.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 6, pp. 3–9, June, 1991. 相似文献
15.
| 1. |
The problem of energy dissipation of the flow remains one of the most important in constructing high-head hydraulic structures with pulsating loads.
| | 2. |
During operation of the world's largest gravity-arch dam of the Sayano-Shushenskoe hydrostation, the energy of the flow being discharged is dissipated by a stilling basin. It was established that the powerful dynamic impulses created in this case originate, among others, from the baffle platform and its foundation. The latter circumstance requires the provision of reliable tightness of the joints between the blocks composing the platform and deep solid transition of the platform with its foundation.
| | 3. |
For the first time in domestic hydrotechnical practice fastening of the platform of the stilling basin by means of advance grouting and prestressed anchors installed to a depth greater than 20 m was mastered on the construction of the Sayano-Shushenskoe dam.
| | 4. |
Works on the manufacture, transport, assembly, tensioning, and testing PSAs were successfully mastered by the Krasnoyarsk enterprise of Gidrospetsstroi. A number of innovations were introduced at the know-how level.
| | 5. |
Passage of the 1992 floodwaters at the elevation of the NPL, after pumping water from the stilling basin, showed the effectiveness of the repair and restoration measures taken, which indicates the correctness of the selected designs, optimal technology, and high quality of the works of Gidrospetsstroi.
| | 6. |
An analysis of the strengthening works for high-head structures under analogous conditions permits recommending the following measures for designing and constructing a stilling basin:
grouting of the foundation in the region of the stilling basin to a depth of 30–40 m; 相似文献
16.
| 1. |
The adopted design and construction schemes for the dam made it possible to place, under complex geologic and hydrologic conditions, the dam fills without trench construction or drainage, which permitted starting sooner the fill placement work and sharply reduced the construction cost.
| | 2. |
For the dam engineering work, use was made of national and foreign experience in construction of high rock-earth dams -the dam core was constructed using clay-skeleton soil fills; the developed transition zones were made using fills consisting of inexpensive natural soils, which made it possible to eliminate the use of artificial mixes; and zoned placement of soils in the dam shells was carried out.
| | 3. |
The construction method and sequence made it possible to build the dam under complex climatic conditions within the established period and to use soils from useful excavations almost exclusively.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 6, pp. 12–16, June, 1991. 相似文献
17.
| 1. |
The technology of sealing with the use of grouts with an adjustable fluidity loss time (GAFLT), developed at Gidrospctsproekt and successfully introduced on the construction of the Inguri arch dam, is universal and makes possible high-quality grouting of joints with a high degree of their leakiness.
| | 2. |
The new technology has indisputable advantages over the existing technology. It provides a high quality of the work and is cost effective, enabling a substantial reduction of labor expenditures and nonproductive losses of cement.
| | 3. |
The GAFLT technology can be recommended for inclusion in building codes and can be used when scaling concrete dams under construction.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 34–37, October, 1990. 相似文献
18.
| 1. |
Results of full-scale observations of overall displacements of the dam, the behavior of joints between sections, settlements of the rock base, and seepage processes in the dam and its base indicate good technical condition of the structure noted throughout the 20 years of its operation.
| | 2. |
Indices of the operating structure's condition, on the whole, correspond to design expectations.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 37–41, November, 1992. 相似文献
19.
| 1. |
The unique arch dam of the Chirkey hydroelectric power plant is operating under difficult conditions of high natural and excited seismicity under a geodynamic load from the left bank, which is not well defined. Reliable design solutions and the safety factor of the concrete have permitted its reliable operation to date.
| | 2. |
The rock mass enclosing the dam exhibits appreciably lower reliability. The clay interlayers contained in the rock and the pattern of dislocation lower the shear strength under the influence of saturation, changes in the upper-pool level, and repeated earthquakes. The safety of the hydraulic facility is determined by the stability of the laft-bank/dam/right-bank system under left-bank creep caused by the gravitational imbalance of the site.
| | 3. |
To retain the proper level of reliability and safety of the Chirkey hydroelectric power plant, it is necessary to perform check geomechanical calculations and organize state-of-art monitoring of geodynamic processes and an earthquake-forecasting service.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 30–35, May, 1994. 相似文献
20.
| 1. |
The Zeya dam is in a satisfactory state, but is operating under conditions different from the design assumptions, under the effect of geodynamic forces — natural and induced seismicity with mainly a transverse direction of the earthquake and, probably, creep pressure from the right bank.
| | 2. |
The design model of a plane stress state adopted in the design does not correspond to the real conditions of the static behavior of the structure which is in a volume stress state. The presence of dynamic loads requires determination of the dynamic characteristics of the structure and corresponding check calculations.
| | 3. |
The geodynamic effect on the SSS of the dam requires improvement of the system of on-site observations and the organization of a geodynamic test area at the Zeya hydrostation in accordance with the decisions of the Ministry of Fuel and Energy of the Russian Federation. Before the creation of this test area the geodynamic effects should be monitored by the available measuring instruments according to the method of OIFZ and VNIIG.
| | 4. |
The existing structural members of the deck of the cavities between buttresses require improvement with consideration of their new, antiseismic function, their incorporation into the calculation scheme, and equipping with measuring instruments.
| | 5. |
The state of the dam and conditions of its operation require the creation of a mathematical model of the structure with consideration of the results of on-site observations and creation of a data bank for predictive purposes.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 8–15, May, 1995. 相似文献
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